Korean J Radiol.  2018 Feb;19(1):153-157. 10.3348/kjr.2018.19.1.153.

In-vivo Visualization of Iron Oxide Enhancement in Focal Pulmonary Inflammatory Lesions Using a Three-Dimensional Radial Gradient-Echo-Based Ultrashort Echo Time Sequence: A Preliminary Study

• Yoon SH
• Lee C
• Park J
• Goo JM
• Park JY

• KMID: 2425121
• DOI: http://doi.org/10.3348/kjr.2018.19.1.153

Abstract

OBJECTIVE
To preliminarily evaluate technical feasibility of a dual-echo ultrashort echo time (UTE) subtraction MR imaging by using concurrent dephasing and excitation (CODE) sequence for visualization of iron-oxide enhancement in focal inflammatory pulmonary lesions.
MATERIALS AND METHODS
A UTE pulmonary MR imaging before and after the injection of clinically usable superparamagnetic iron-oxide nanoparticles, ferumoxytol, was conducted using CODE sequence with dual echo times of 0.14 ms for the first echo and 4.15 ms for the second echo on 3T scanner in two rabbits concurrently having granulomatous lung disease and lung cancer in separate lobes. A mean ratio of standardized signal intensity (SI) was calculated for comparison of granulomatous lesion and cancer at first echo, second echo, and subtracted images. Lesions were pathologically evaluated with Prussian blue and immunohistochemistry staining.
RESULTS
Post-contrast subtracted CODE images visualized exclusive enhancement of iron oxide in granulomatous disease, but not in the cancer (mean ratio of SI, 2.15 ± 0.68 for granulomatous lesion versus 1.00 ± 0.07 for cancer; p value = 0.002). Prussian blue and corresponding anti-rabbit macrophage IgG-staining suggested an intracellular uptake of iron-oxide nanoparticles in macrophages of granulomatous lesions.
CONCLUSION
Dual-echo UTE subtraction MR imaging using CODE sequence depicts an exclusive positive enhancement of iron-oxide nanoparticle in rabbits in focal granulomatous inflammatory lesions.

Keyword

Magnetic resonance imaging; Nanoparticles; Iron; Macrophages; Lung neoplasms; Granuloma

MeSH Terms

Ferrosoferric Oxide
Granuloma
Immunohistochemistry
Iron*
Lung Diseases
Lung Neoplasms
Macrophages
Magnetic Resonance Imaging
Nanoparticles
Rabbits
Ferrosoferric Oxide
Iron

Figure

• 

  Fig. 1 Representative axial dual-echo CODE images on 3T MR scanner (A-F), and histopathologic Prussian blue, anti-rabbit macrophage IgG-stained images (G-I) of concurrent granulomatous lung lesion (right lower lobe, white arrowhead) and lung cancer (left lower lobe; black arrowhead) in rabbit. Images were obtained prior to intravenous administration of ferumoxytol (12 mg/kg) (A–C), 24 hours after injection (D–F). Baseline first (TE, 0.17 msec) and second echo (TE, 4.15 msec) images revealed similar mass-like consolidation in both basal lungs (A, B). When subtracted, there was identical signal nulling in granulomatous lung lesion and lung cancer (C). Ferumoxytol-enhanced MR images depicted higher SI at first echo and lower SI at second echo in granulomatous lung lesion if compared to those in lung cancer (D, E). When subtracted, there was obvious enhancement in granulomatous lung lesion whereas signal nulling in lung cancer (F). Prussian blue-stained slice revealed dense intracellular accumulation of iron oxide nanoparticles (× 400, G). Prussian blue and corresponding anti-rabbit macrophage IgG-staining slices revealed intracellular uptake of iron oxide nanoparticles in macrophages (black arrows) (× 400, H, I). CA = contrast administration, CODE = concurrent dephasing and excitation, SI = signal intensity, TE = echo time

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